// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_THREAD_TASK_RUNNER_HANDLE_H_
#define BASE_THREAD_TASK_RUNNER_HANDLE_H_

#include "base/base_export.h"
#include "base/memory/ref_counted.h"

namespace base {

class SingleThreadTaskRunner;

// ThreadTaskRunnerHandle stores a reference to a thread's TaskRunner
// in thread-local storage.  Callers can then retrieve the TaskRunner
// for the current thread by calling ThreadTaskRunnerHandle::Get().
// At most one TaskRunner may be bound to each thread at a time.
// Prefer SequenceTaskRunnerHandle to this unless thread affinity is required.
class BASE_EXPORT ThreadTaskRunnerHandle {
public:
    // Gets the SingleThreadTaskRunner for the current thread.
    static scoped_refptr<SingleThreadTaskRunner> Get();

    // Returns true if the SingleThreadTaskRunner is already created for
    // the current thread.
    static bool IsSet();

    // Binds |task_runner| to the current thread. |task_runner| must belong
    // to the current thread for this to succeed.
    /*explicit*/ ThreadTaskRunnerHandle(
        scoped_refptr<SingleThreadTaskRunner> task_runner);
    ~ThreadTaskRunnerHandle();

private:
    scoped_refptr<SingleThreadTaskRunner> task_runner_;
};

} // namespace base

#endif // BASE_THREAD_TASK_RUNNER_HANDLE_H_
